Abstract:

Objective

To investigate the surface-enhanced Raman spectroscopy （SERS） of Streptococcus mutans （S.mutans） with active silver colloid nanoparticles as the substrate.

Methods

Silver colloids were produced for SERS experiments by reduction of silver nitrate with glucose. SERS of S.mutans were collected using a DXR laser micro Raman spectrometer.

Results

The silver nanoparticles were spherical with 11.08 nm mean size which had better dispersibility and higher enhanced effect. The SERS of S.mutans had higher Raman signal intensity and more Raman peaks. The bands enhanced spectral peaks in the 700 cm^-1 ～1800 cm^-1 region were assigned to bacterial cell wall， according to the obtained SERS of S.mutans. In particular， at 721.94， 1270.35， 1371.83， 1441.51， 1569.22， 1628.91，2922.65 cm^-1 regions had significant Raman peaks.

Conclusions

We can get SERS of S.mutans with silver colloid nanoparticles as active substrate which was prepared by reduction of silver nitrate with glucose as reducing agent. With SERS， we can detect S.mutans and analysis the composition of its cell wall. Hence， it has a great potential for further exploration the cariogenic mechanism of S.mutans， and to develop new methods to anti-caries in future study.

Key words: Streptococcus mutans, Dental caries, Spectrum analysis,raman, Silver nanoparticles, Colloid